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LY4337713 for people with FAP-positive ovarian, breast, pancreatic, colorectal, or esophageal cancers

A Dose Escalation and Dose Optimization Phase 1a/1b Study to Evaluate Safety, Tolerability and Dosimetry of Radioligand Therapy With LY4337713 in Adults With FAP-Positive Solid Tumors (FiREBOLT)

Phase 1 Interventional Eli Lilly and Company · NCT07213791

This trial tests LY4337713, a FAP-targeted lutetium-177 therapy, in people with advanced cancers that show high levels of fibroblast activation protein (FAP).

Quick facts

PhasePhase 1
Study typeInterventional
Enrollment241 (estimated)
Ages18 Years and up
SexAll
SponsorEli Lilly and Company Industry-sponsored
Drugs / interventionsCAR-T, chimeric antigen receptor, immunotherapy, radiation
Locations28 sites (Newport Beach, California and 27 other locations)
Trial IDNCT07213791 on ClinicalTrials.gov

What this trial studies

LY4337713 is a lutetium-177–labeled agent designed to bind fibroblast activation protein (FAP) in the tumor microenvironment and deliver targeted radiation. This Phase 1 interventional trial enrolls adults with selected advanced or metastatic solid tumors that are confirmed FAP-positive to characterize safety, side effects, and early signs of anti-tumor activity. The study includes pharmacokinetic sampling to measure how the drug enters the bloodstream, is metabolized, and is cleared, and participants are followed for about five years. Treatment is administered at participating U.S. sites with dosing and schedule determined by the phase 1 protocol.

Who should consider this trial

Good fit: Adults with histologically or cytologically confirmed advanced or metastatic tumors that test positive for FAP expression and who meet the prior-treatment requirements for their cancer type are the intended participants.

Not a fit: Patients whose tumors do not express FAP, who have early-stage disease with curative options, or who have contraindications to radionuclide therapy or poor organ function are unlikely to benefit from this intervention.

Why it matters

Potential benefit: If successful, LY4337713 could shrink or slow growth of FAP-expressing tumors by delivering targeted radiation and may offer a new option for patients who have exhausted standard treatments.

How similar studies have performed: Radioligand therapies using lutetium-177 (for example PSMA-targeted treatment in prostate cancer) have demonstrated clinical benefit, and early-phase FAP-targeted radioligands have shown promising but preliminary signals.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* Must have clinical or imaging evidence of fibroblast activation protein (FAP) expression per local assessment
* Must have histologically or cytologically confirmed diagnosis of one of the following:

  * Adenocarcinoma of the pancreas
  * Hormone receptor (HR)-positive human epidermal growth factor 2 (HER2)-negative breast cancer
  * HER2-positive breast cancer
  * Triple negative breast cancer (TNBC)
  * Platinum-resistant or refractory ovarian cancer (including ovarian carcinosarcoma)
  * Other solid tumors

    * Gastric cancer (adenocarcinoma)
    * Colorectal cancer (CRC)
    * Esophageal cancer (squamous cell carcinoma or adenocarcinoma)
    * Cholangiocarcinoma
* Must have received prior treatments as indicated below:

  * Phase 1a

    * Adenocarcinoma of the pancreas: Participants must have received at least 1, but no more than 2 prior regimens for locally advanced unresectable or metastatic disease.
    * HR-positive HER2-negative breast cancer: Participants must have received less than or equal to (≤)5 prior lines of treatment for advanced or metastatic disease, which must include a cyclin-dependent kinase 4/6 inhibitor.
    * HER2-positive breast cancer: Participants must have received at least 2 lines of HER2-targeted therapy, which should include at least 1 antibody-drug conjugate (ADC) for metastatic disease (if locally available).
    * TNBC: Participants must have received at least 2 lines of therapy for metastatic disease.
    * Platinum-resistant or refractory ovarian cancer: Participants must have received or after at least 1 platinum-based therapy.
    * Other solid tumors (gastric cancer, CRC, esophageal and cholangiocarcinoma): Participants must have received greater than or equal to (≥)1 prior line of systemic therapy for advanced or metastatic disease; including prior line(s) in combination with immunotherapy or vascular endothelial growth factor inhibitor.
  * Phase 1b:

    * Participants must have advanced or metastatic solid tumors and have received ≥1 prior line of therapy.
* Must have an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 to 1.
* Measured creatinine clearance ≥60 milliliters per minute (mL/min)

Exclusion Criteria:

* Have known active central nervous system (CNS) metastases or carcinomatous meningitis.
* Have significant cardiovascular disease
* Have prolongation of the corrected QTcF \>470 milliseconds (msec) during screening. QTcF is calculated using Fridericia's Formula: QTcF = QT/(RR0.33)
* Have evidence of ongoing and untreated urinary tract obstruction
* Had previous hemi- or total-body radiation.
* Had previous adoptive T-cell therapy (e.g., chimeric antigen receptor T-cell \[CAR-T therapy, T-cell receptor \[TCR\] therapy, etc.)
* Unable to lie flat during, or otherwise tolerate, single photon emission computed tomography (SPECT), positron emission tomography (PET), computed tomography (CT) or magnetic resonance imaging (MRI).

Where this trial is running

Newport Beach, California and 27 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Ovarian NeoplasmsBreast NeoplasmsPancreatic Intraductal NeoplasmsColorectal NeoplasmsEsophageal NeoplasmsStomach NeoplasmsCholangiocarcinomaCancer-associated fibroblasts
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.